In percussion musical instruments a tone generator is struck by percussion means to generate vibration to be translated into sound. The term "tone generator" as herein used is intended to include vibratory tone producers or vibratory sound sources of percussion musical instruments vibrated by impacts thereon and producing sound acoustically or electrically.
As an example, an electric piano basically consists of tuned reeds called tone generators which are struck with hammers which latter are actuated in the usual ways by keys so that when the keys are depressed the respective corresponding hammers strike the respective tone generators. In an electric piano the vibrations of the tone generators are sensed by magnetic pick-ups and thus an electric signal is produced which is amplified and translated by the usual electric circuit into signals to drive a loudspeaker or loudspeakers.
The primary object of this invention is to selectively shift the relative position between the tone generator and the impactor so as to vary the location of the impact on the tone generator, namely, shifting the striking line at will during playing so that a new type of sound is generated by the simple manipulation of a foot pedal or the like so that the tone change is controlled by the player. The shifting of the striking line alters the wave shape, the harmonic structure and the volume level of the sound generated by the percussion instrument. In the herein specification "tone change" refers to these alterations of the tone.
Another object of the invention is to divide the wiring of the tone generators so as to separate the electronic circuit of about the first octave at the bass end of the keyboard and the last one and one-half octaves at the treble end so they are separately operated electronically because the notes in those areas are hardly affected by the "tone change"; but the remaining tone generators in the middle are affected by the shifting of the harp in various degrees, namely, each note has an individual response based on its timbre, volume and tone adjustment, therefore, an amplifying circuit is utilized to compensate for the corresponding loss of their overall volume.
Further object of the invention is to provide a simple and facile mechanism for changing the relation between the tone generator assembly and the percussion elements, such as the hammers, for changing the tone of the sound selectively to any degree desired by the player during the playing of the musical instrument.